Method and system for processing video data in a multipixel memory to memory compositor

ABSTRACT

A method and system for processing video data using multi-pixel scaling in a memory system are provided. The multi-pixel scaling may include reading pixel data for one or more data streams from the memory system into one or more scalers, wherein each of the plurality of data streams includes a plurality of pixels, scaling the pixel via the one or more scalers and outputting the scaled pixels from the one or more scalers. Pixel data may be sequential or parallel. The plurality of scalers may be in parallel, scaling sequential pixel data with independent phase control, or scaling parallel pixel data in substantially equal phase. Pixel data may be transposed, replicated, distributed and aligned prior to reading by scalers, and may be aligned merged and transposed after scaling. Scaling may include interpolation or sub sampling using pixel phase, position, step size and scaler quantities.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

Not Applicable

FIELD OF THE INVENTION

Certain embodiments of the invention relate to processing of video data. More specifically, certain embodiments of the invention relate to a method and system for processing video data in a multi-pixel memory to memory compositor.

BACKGROUND OF THE INVENTION

Motion pictures, video and digital photography use compositing to alter image quality or create visual effects by combining images from different sources. Images and colors may be altered by manipulating pixels through color conversion, keying, scaling and blending operations. Compositing is used extensively in modern film, television and photography to achieve effects that otherwise would be difficult or not cost-efficient. One common use for compositing is to shoot on a relatively small set and create the impression of a significantly different location by adding additional surrounding and foreground imagery. A common tool to help facilitate composites is using a blue or green backdrop of a uniformly solid color that is placed behind an actor or object. During compositing, all areas of a frame with that color are removed and replaced, allowing the compositor to place the isolated image of the actor or object in front of a separately shot or synthetic background.

Compositing technique is commonly done using digital techniques. One of the known digital techniques is a raster operation (ROP) where changes of image graphics may be transitioned smoothly by compositing the source image data to the destination image data through programming a ROP table. A digital image may be reproduced by clustering pixels or dots of varying intensity and color, forming a raster graphics image. A colored raster graphic image will usually have pixels with between one and eight bits for each of the basic colors red, green, and blue components (R, G, B). By using red, green and blue intensities, many color combinations can be represented. Typical display adapters may use up to 24 bits of information for each pixel. This is usually apportioned with 8 bits each for red, green and blue, giving a range of 256 possible values, or intensities, for each hue. With this system, (256³ or 2²⁴) discrete combinations of hue and intensity may be specified.

With the need for compositing images comes a variant of RGB which includes an extra 8 bit channel for transparency, thus resulting in a 32 bpp format. The transparency channel is commonly known as the alpha channel, so the format is named RGBA. Since the RGBA does not change anything in the RGB model, it is not a distinct color model. The RGBA is a file format which integrates transparency information along with the color information in the same file. This allows for alpha blending of the image over another, and is a feature of the PNG format.

In graphics and visual effects, keying is an informal term for compositing two full frame images together, by discriminating the visual information into values of color and light. Some of the common key types: chroma key, luma key, difference key and matte key. A chroma key is the removal of a color from one image to reveal another “behind” it. A luma key similarly replaces color from an image which falls into a particular range of brightness. This technique is less controllable, but may be used on graphic elements. It is particularly useful for realistic fire keying. A difference key uses a background plate of the scene that the foreground object is being keyed out of and the software then assesses the source video and any pixels that don't match the grid are obviously meant to be keyed out. For example, if your subject is standing in front of a wall, a photo taken from the camera of the same wall is used. This may be taken from the same camera angle, focus & distance. The software may then compare the video to be keyed with the original photo and generates a mask based upon that difference.

The quality of a raster graphic image is determined by the total number of pixels (resolution), and the amount of information in each pixel (often called color depth). For example, an image that stores 24 bits of color information per pixel can represent smoother degrees of shading than one that only stores 16 bits per pixel. Likewise, an image sampled at 640×480 pixels (therefore containing 307,200 pixels) will look rough and blocky compared to one sampled at 1280×1024 (1,310,720 pixels).

Because it takes a large amount of data to store a high-quality image, data compression is used to reduce the memory size and may result in some loss of resolution in raster graphics image. The amount of memory space used by an uncompressed image is specified by the number of pixels in the image and the color depth to which each pixel may be specified. In a 24-bit image, each pixel may be specified by a 24-bit allocation of memory, so the amount of space required in bits is 24× the number of pixels. For example, a 24-bit image 640×480 pixels in size requires (24×640×480)/8=921,600 bytes of memory.

Compositing two images of different sizes require scaling of one image to the other. Scaling is a non-trivial process that involves a trade-off between speed, smoothness and/or sharpness. Image scaling may involve either scale down by sub-sampling or zooming out (reducing or shrinking an image) or scale up by zooming in (enlarging an image). When increasing or reducing the size of images, the problem of processing efficiency becomes particularly evident because of the fact that digital images are composed of large number of pixels.

Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A method and system is provided for processing video data in a multi-pixel memory to memory compositor, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an exemplary video data processing operation of a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 2 is a block diagram illustrating exemplary functions in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 3 is a block diagram that illustrates an exemplary parallel multi-pixel data processing block in a memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 4A is a block diagram that illustrates an exemplary vertical scaling in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 4B is a block diagram that illustrates using vertical scalers for horizontal scaling in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 4C is a diagram that illustrates the uses of vertical scalers for both vertical and horizontal scaling in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 4D is a block diagram that illustrates another embodiment using same vertical scalers for both vertical and horizontal scaling in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 5 is a block diagram that illustrates an exemplary vertical scale down or scale up processes in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 6 is a block diagram that illustrates an exemplary vertical scaler that utilizes fewer pixels per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 7A is a block diagram that illustrates exemplary horizontal scaling using a single-pixel per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 7B is a block diagram that illustrates exemplary horizontal scaling using two pixels per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 7C is a block diagram that illustrates exemplary horizontal scaling using four pixels per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 8 is a block diagram that illustrates exemplary phase and step size relationship of output pixels from a plurality of parallel horizontal scalers, in accordance with an embodiment of the invention.

FIG. 9A is a block diagram that illustrates exemplary multi-pixel per clock cycle horizontal scaler for a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 9B is a is a block diagram that illustrates exemplary use of four horizontal scalers for both horizontal and vertical scaling in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 10 is a flow chart that illustrates exemplary steps for vertical scaling of a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

FIG. 11 is a flow chart that illustrates exemplary steps for horizontal scaling of a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method, system or program for processing video data in a multi-pixel memory to memory compositor. In an aspect of the invention, video data in the form of pixel data from the memory system may be read into one or more scalers for scaling. The read pixel data may comprise one or more data streams, each of which may comprise a plurality of pixels. The pixels may be scaled by one or more scalers with a scaling factor in a clock cycle and output to the memory to memory compositor system. The data streams may comprise sequential or parallel pixels. The sequential pixels may be processed by one or more horizontal scalers. Each of the sequential pixels may be replicated by a distributor control and aligned for horizontal scaling. The replicated and aligned pixels may be scaled using independent phase control interpolation where the interpolation is derived from a pixel phase value, a step size value and number of the horizontal scalers used. The scaled pixels may be merged by a merge control to create an output sequential data stream. The parallel pixels may be scaled in substantially equal phase by one or more vertical scalers.

Various embodiments to the invention may comprise using vertical scalers to perform horizontal scaling function or using horizontal scalers to perform vertical scaling function. This may be achieved by transposing the pixels before being read by the vertical or horizontal scalers. A symmetrically scaled image may be generated by a vertical scaling and a horizontal scaling process, or by one or more vertical scaling with one or more transposing pixels process, or a one or more horizontal scaling with one or more transposing pixels process. In an exemplary embodiment of the invention, a twice vertical scaling and twice transposing pixels process, or a twice horizontal scaling and twice transposing pixels process may be used for symmetrical scaling. In general, plurality of combinations of vertical scaling or horizontal scaling, using one or more transposed pixel processing may yield scaling to any desired aspect ratio.

FIG. 1 is a block diagram illustrating an exemplary video data processing operation of a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 1, there is shown a multi-pixel memory to memory compositor system 100. The multi-pixel memory to memory compositor system 100 may comprise a memory system 102 and a memory to memory compositor (M2MC) 120.

The memory system 102 may be a DRAM, a flash memory or any suitable media storage that may be utilized for storing images such as a first image 106 and a second image 110 to be processed by the M2MC 120. The first image 106 may be a source image illustrated as a baseball 104 comprising pixel data 114. The second image 110 may be a destination image illustrated as a baseball player 112 with background 108 comprising pixel data 116.

The M2MC 120 may be viewed as a data-processing pipeline which may read and process the first and second images 106 and 110 respectively from the pixel data 114 and pixel data 116 as inputs and optionally composites first and second images 106 and 110 respectively into pixel data 118 as an output to be stored as an output image 110 a in memory system 102. The output image 110 a may be a composite image of an un-scaled baseball player 112 a from the second image 110 with background 108 a with a scaled down baseball 104 a from the first image 108. The choice of scaling the first or second image may be interchangeable as long as one of the images is kept at a fixed scale as a dimensional reference for compositing. The M2MC 120 may read pixel data 114 and 116 and writes pixel data 118 to the memory system 102 in a real time/non-real time system.

In an embodiment of the invention, the pixel data 114 and 116 may comprise one or more data streams where each data stream may comprise a plurality of pixels. The throughput of the M2MC 120 may be increased by processing in parallel a plurality of input pixels. The parallel processing of pixels may be achieved vertically or horizontally according to various embodiments of the invention.

FIG. 2 is a block diagram illustrating exemplary functions in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 2, there is shown a multi-pixel memory to memory compositor system 200. The multi-pixel memory to memory compositor system 200 may comprise a memory system 202 previously described in FIG. 1 and a memory to memory compositor (M2MC) 212. The M2MC 212 may comprise a source module 204 for source image pixel data processing, a destination module 206 for destination image pixel data processing and a blend module 208 for pixel data compositing. The source module 204, destination module 206 and blend module 208 may form suitable logic, circuitry, and/or code that may enable control, management, and/or pixel data storage operations, for example.

The source module 204 for source image pixel data processing may comprise a source feeder 220 a, a first source crossbar 222 a, a color key block 226 a, a color matrix block 228 a, a scaling block 229 and a second source cross bar 230 a. The destination module 206 for destination image pixel data processing may comprise a destination feeder 220 b, a first destination crossbar 222 b, a color key block 226 b, a color matrix block 228 b, and a second destination cross bar 230 b. The blend module 208 for pixel data compositing may comprise a blend function block 232, a Raster operation block ROP 234, an output selection block 236 and an output matrix and feeder 238.

The source module 204 and the destination module 206 may operate in a somewhat similar manner except that no scaling operation may be performed in the destination module 206. The destination pixel data 216 may be used as a dimensional reference when compositing with the source pixel data 214 thus scaling may not be required in the destination module 206. In another embodiment, scaling may be performed in the destination module 206 similar to the source module 204.

The source feeder 220 a and destination feeder 220 b may each comprise a buffer for storing and shifting corresponding source pixel data 214 and destination pixel data 216 into the first source cross bar 222 a and first destination cross bar 222 b respectively. The first source cross bar 222 a and the first destination cross bar 222 b may each comprise a switch matrix to route the respective source pixel data 214 and the destination pixel data 216 for the next operations.

The color key blocks 226 a and 226 b may each operate with chroma key, luma key, difference key and matte key operations from respective inputs—the source input (first source cross bar 222 a) or the destination input (first destination cross bar 222 b). Keying operation may comprise compositing between two respective frames of images together (both source images or both destination images) and discriminating the visual information of respective source pixel data 214 or destination pixel data 216 into desired range of color and light.

The color matrix block 228 a and 228 b may perform color conversion to pixels input respectively from first source cross bar 222 a and first destination cross bar 222 b. Color conversion may be done by adjusting each respective pixel color on a 0 to 255 scale to attain consistency between source and destination pictures. For example: One of the pictures may be in YUV format while the other one may be in RGB format, so color matrix operation converts YUV to RGB (or vice versa) before they can be blended together. The scaling block 229 scales the source pixel data 214 b inputs from the first source cross bar 222 a. The scaling block 229 may comprise one or more vertical scalers or horizontal scalers where scaling of source pixel data 214 b may be performed according to one or more scaling factors defined by a user input.

Similar to the first source cross bar 222 a, the second source cross bar 230 a may comprise a switch matrix to route the respective outputs 245 a to 245 c from the color key block 226 a, color matrix block 228 a or scaling block 229 to the next operation. In an embodiment of the invention, the pixel processing operations of color key block 226 a, color matrix block 228 a or scaling block 229 may be performed in any order to be defined in software programming.

In an instance, the source pixel data 214 a may be programmed to be scaled in the scaling block 229 first, color key block 228 a second and color matrix block 228 a last. Hence, the second source cross bar 230 a may direct source output pixel data 242 a or 244 a to the blending block 208. The output 245 c of scaling block 229 may be returned to the first source cross bar 222 a through output 246 a for the next operation in the color key block 226 a. The output 245 a from the color key block 226 a may be returned to the first source cross bar 222 a through output 246 b to complete the operation by the color matrix block 228 a. Simultaneously the scaling block 229 and the color key block 226 a may continue to read and process new pixel data 214 b from the first source cross bar 222 a to complete the pixel data operations in the source module 204.

Likewise, destination pixel data 216 a may first be processed by color matrix block 228 b to produce output 245 e, where the second destination crossbar 230 b may returned output 245 e to the first destination cross bar 222 b through output 246 c for the next operation in color key block 226 b. Simultaneously the color matrix block 228 b may continue to read and process new pixel data 216 a from the first source cross bar 222 a for the subsequent pixel data operations in the destination module 206.

The blend module 208 for pixel data compositing may receive outputs 242 a and 244 a from the source module 204 and outputs 242 b, 244 b and 248 from the destination module 206. A plurality of compositing operations may be performed on the outputs from both the source module 204 and destination module 206. In a time instant, pixels from outputs 242 a and 242 b may super-imposed in the blend function block 232 to produce outputs 250 or 252.

In another time instant, a Raster operation in the Raster operation block ROP 234 may be performed on pixels from outputs 248 and 250 to achieve a smooth graphical transition effect. The output selection block 236 may select any combination of outputs 244 a, 244 b, 252 and 256 to perform a second color matrix operation at the output matrix and feeder 238 to produce an output 218 as completion of the multi-pixel module to module compositor operation. The output 218 may be stored in the memory system 202.

FIG. 3 is a block diagram that illustrates an exemplary parallel multi-pixel data processing block in a memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 3, there is shown a parallel multi-pixel data processing block 300 comprising a plurality of pixel processing blocks 312 to 318 with pixel inputs X₀ 302 to X₃ 308 and corresponding pixel outputs Y₀ 322 to Y₃ 328. The plurality of pixel processing blocks 312 to 318 in parallel arrangement may perform operations such as color keying, color matrixing, blending, or ROP. The throughput of processing pixels data is proportionately increased.

Each of the pixel processing blocks 312 to 318 may be represented by one or more functional blocks within the memory to memory compositor (M2MC) 212 comprising color key block 226 a, color matrix block 228 a, blend function block 232, or ROP 234 shown in FIG. 2.

The value of the output pixel Y₀ 322 may depend on the value of one input pixel X₀ 302 only. For example, the output of the color-matrix may be described by the following relationship: Y _(n) =f(X _(n) ,C),

where: X_(n) is the n-th pixel of input, C defines the transformation parameters, and Y_(n) is the n-th pixel of the output

The behavior of color-key, blend and ROP operations may also be described in a similar manner. For example, color-key operation may be defined with the above equation, if the parameter C specifies the range of colors to be keyed out.

Increasing the pixel processing throughput for these pixel processing blocks 312 to 318 (key, matrix, blend and ROP) is a simple matter of increasing the parallelism by using beyond pixel processing blocks 312 to 318. Each of the parallel data paths may be fed n-horizontally to adjacent input pixels (X₀, X₁, X₂, X₃) to processing blocks 312 to 318 to output respective n-adjacent pixels (Y₀, Y₁, Y₂, Y₃).

FIG. 4A is a block diagram that illustrates an exemplary vertical scaling in a multi-pixel memory to memory compositor system 400A, in accordance with an embodiment of the invention. Referring to FIG. 4, there is shown in the multi-pixel memory to memory compositor system 400A comprising a stripe buffer filing logic (SBFL) 427 a, a plurality of parallel pixel data streams X₀ 414 a to X₃ 414 d, a memory buffer 415 m, a plurality of vertical scalers S₀ 429 a to S₃ 429 d and a plurality of respective parallel output pixel data streams Y₀ 418 a to Y₃ 418 d.

The stripe buffer filing logic (SBFL) 427 a may comprise a memory buffer with suitable logic and circuits storing pixel data 414. The pixel data 414 in the memory buffer are logically partitioned for striping to a plurality of parallel pixel data streams X₀ 414 a to X₃ 414 d. The memory buffer may comprise flash memory, DRAM or any suitable memory storage with fast access time. The striping of pixel data 414 may be follow a first in first out (FIFO) distribution pattern or may be logically mapped according to a table. The striping of pixel data 414 may be managed or controlled by a controller or processor such as a phase accumulator and control (shown in FIG. 5) to partition pixel data 414 into the parallel pixel data streams X₀ 414 a to X₃ 414 d read by a plurality of vertical scalers S₀ 429 a to S₃ 429 d.

For example, the (SBFL) 427 a may partition the pixel data 414 into four parallel pixel data streams X₀ 414 a to X₃ 414 d for vertical scaling. Each pixel data stream may represent a vertical section of an image of a picture (shown in FIG. 4C), in this example the picture may be partitioned into four sections for vertical scaling. A high number of partitions may represent more parallel processing.

Each of the pixel data streams X₀ 414 a to X₃ 414 d may carry chunks of pixel data to be processed. For example, pixel data streams X₀ 414 a may comprise pixels X_(0,0), X_(1,0), X_(2,0), X_(3,0) X_(4,0) X_(5,0) . . . . Likewise, pixel data streams X₁ 414 b to X₃ 414 d X₀ may comprise pixels X_(0,1) to X_(5,1) . . . , and X_(0,3) to X_(5,3), X_(4,0) X_(5,0) respectively.

The memory buffer 415 may be logically partitioned into a plurality of memory spaces 415 a to 415 d to hold the pixels from the respective pixel data streams X₀ 414 a to X₃ 414 d. The number of pixels to be processed in the scaling operation may vary by design. For illustration, if a 6-tap scaling filter may be used, each of the plurality of memory spaces 415 a to 415 d may hold up to six pixels at a time such as pixels X_(0,0) to X_(5,0) represented by a pixel column in memory space 415 a. Pixel row 414 e holding horizontal pixels X_(0,0) to X_(0,3) may be processed down the columns in sequential order. For example, when the first pixel row 414 e is being scaled by scalers S₀ 429 a to S₃ 429 d, a subsequent pixel row of data such as X_(6,0) to X_(6,3) or a next chunk of pixel data starting with X_(0,4) to X_(0,7) may be shifted into the memory buffer 415 from the stripe buffer filing logic 427.

Each of the plurality of vertical scalers S₀ 429 a to S₃ 429 d may comprise a digital filter such as a finite impulse response filter (FIR filter). The FIR filter is ‘finite’ because its response to an impulse ultimately settles to zero. This is in contrast to infinite impulse response (IIR) filters which have internal feedback and may continue to respond indefinitely. The FIR filter has some advantageous properties since it may be inherently stable and requires no feedback so that rounding of errors may not be compounded and can have linear phase. In parallel vertical scaling, the pixels may be scaled in substantially equal phase using the same scaling factor in S₀ 429 a to S₃ 429 d.

Each of the pixels Y₀ 414 a to Y₃ 414 d at the output may represent a scaled value calculated from a plurality of vertical neighboring pixels from each of the pixel data streams X₀ 414 a to X₃ 414 d at the input. Scaling may be performed by FIR filters within the vertical scalers S₀ 429 a to S₃ 429 d based on a scaling factor and the positions of the pixels. A FIR filter may define how an input signal is related to the output signal by the following relationship:

$Y_{n} = {\sum\limits_{i = 0}^{4}{A_{i}*X_{n + {({i - 2})}}}}$ where i is a variable defined by the pixel sampling size for calculation, n is the pixel position, A is a coefficient, and X is the input pixel value.

It may be desirable to generate an output Y_(n) using a symmetrical FIR filter. A symmetrical output pixel Y_(n) may be achieved by using symmetrical neighboring inputs for calculations. In this example, the output value Y_(n) may depend on five input pixels stored in memory space 415 a. For example an output pixel Y₇ may depend on input pixels X_(5,0), X_(6,0), X_(7,0), X_(8,0), X_(9,0) where the vertical pixel neighbors are X_(5,0), X_(6,0), and X_(8,0), X_(9,0). It may also depend on the values of A₀, A₁, A₂, A₃ and A₄, also known as the coefficients of the filter. In an embodiment of the invention, the coefficients A₀, A₁, A₂, A₃ and A₄ may be defined by a user for scaling calculations or may be preprogrammed as a default. The coefficients A₀, A₁, A₂, A₃ and A₄ may or may not be the same, they may be constant and may not change with n (i.e. the pixel position). Similarly, the value of output pixel Y₈ may depend on input pixels X_(6,0), X_(7,0), X_(8,0), X_(9,0) and X_(10,0). The coefficients A₀, A₁, A₂, A₃ and A₄ associated with each output pixel Y_(n) calculation remains constant.

FIG. 4B is a block diagram that illustrates using vertical scalers for horizontal scaling in a multi-pixel memory to memory compositor system 400B, in accordance with an embodiment of the invention. FIG. 4B is an alternate embodiment of FIG. 4A where vertical scalers S₀ 429 e to S₃ 429 h may be configured for horizontal scaling. FIG. 4B continues with the pixel outputs Y₀ 414 a to Y₃ 414 d of FIG. 4A. Referring to FIG. 4B, there is shown a second SBFL 427 b, a second memory buffer 415 b, a second plurality of vertical scalers S₀ 429 e to S₃ 429 h and a third SBFL 427 f.

In an embodiment of the invention, the second SBFL 427 b may store transposed pixel data 414 m comprising vertically scaled output pixel data streams Y₀ 414 a to Y₃ 414 d from the first vertical scalers S₀ 429 a to S₃ 429 d in FIG. 4A. The second SBFL 427 b under logic control 405 b may be programmed to perform a data mapping operation to transpose vertically scaled output pixels data streams Y₀ 414 a to Y₃ 414 d and stripe the transposed pixel data 414 m into a plurality of horizontal pixel data streams X₀ 414 f to X₃ 414 j for horizontal scaling.

For example, the vertical neighbors X_(0,0), X_(1,0), X_(2,0), X_(3,0) . . . of output pixel data stream Y₀ 418 a shown in FIG. 4A may be transposed to become horizontal neighbors 414 k of parallel pixel data streams X₀ 414 f to X₃ 414 j. Likewise, the horizontal neighbor pixels X_(0,0), X_(0,1), X_(0,2), X_(0,3) . . . of output pixel data streams Y₀ 418 a to Y₃ 418 d shown in FIG. 4A data may be transposed to become vertical neighbor pixels X_(0,0), X_(0,1), X_(0,2), X_(0,3) . . . held in memory space X₀ 415 e.

The second vertical scalers S₀ 429 e to S₃ 429 h may read the plurality of vertically scaled and transposed pixels from the respective memory spaces 415 e to 415 h for a second vertical scaling. The second vertical scaling in the second vertical scalers S₀ 429 e to S₃ 429 h may yield twice vertically scaled transposed output 418 k comprising pixel data streams Y₄ 418 f to Y₇ 4181.

A third SBFL 427 f under a logic control of 405 f may read the twice vertically scaled transposed pixels x to Y₇ 418 i and may perform a second transposition into data 418 t. The logic control 405 f may merge the twice vertical scaled and twice transposed data 418 t into an output 414 h comprising data streams Y′₄ to Y′₇. The effect of twice vertical scaling and twice transposition with the merging function may yield a symmetrical scaling in both vertical and horizontal directions—equivalent to a user zooming in or zooming out an image. The invention is not limited to twice scaling or twice transposition of pixels. Accordingly, any plurality of combinations of vertical scaling or horizontal scaling, using one or more transposed pixel processing may be utilized to yield scaling to any desired aspect ratio.

FIG. 4C is a diagram that illustrates the uses of vertical scalers for both vertical and horizontal scaling in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. The operations of FIG. 4A and FIG. 4B may be combined and illustrated by FIG. 4C using a scale factor of two in each of the vertical scalers. Reference designations from FIG. 4A and FIG. 4 b may be referred to for description.

An image may be stored as pixel data 414. The pixel data 414 may be read by a first SBFL 427 a and striped into four pixel data streams X₀ 414 a to X₃ 414 d to be read by four vertical scalers 429 a to 429 d. The four vertical scalers 429 a to 429 d may vertically scale the pixel data streams X₀ 414 a to X₃ 414 d with a scaling factor of two, doubling the vertical dimension as first vertically scaled output pixel data streams Y₀ 418 a to Y₃ 418 d. The first vertically scaled output pixel data streams Y₀ 418 a to Y₃ 418 d may be read and transposed by a second SBFL 427 b and then striped as input pixel data streams X₀ 414 f to X₃ 414 j.

The transposed input pixel data streams X₀ 414 f to X₃ 414 j may be read by a second four vertical scalers 429 e to 429 h and be vertically scaled a second time to a twice vertically scaled transposed output pixel data streams Y₄ 418 f to Y₇ 418 j. The twice vertically scaled transposed output pixel data streams Y₄ 418 f to Y₇ 4181 may be read by a third SBFL 427 f where a second transposition may take place to generate a twice vertically scaled, twice transposed output pixel data streams Y′₄ 418 j to Y′₇ 418 n. The third SBFL 427 f under a logic control 405 f may merge the output pixel data streams Y′₄ 418 j to Y′₇ 418 n and combine the transposed pixel data into a single image 414 h forming a symmetrically scaled image both vertically and horizontally.

In an embodiment of the invention, the three SBFL 427 a, 427 b and 427 f may all be resided within the same memory buffer with sufficient memory allocations to store the pixel data controlled by independent control logic for independent operation.

FIG. 4D is a block diagram that illustrates using similar vertical scalers for both vertical and horizontal scaling in a multi-pixel memory to memory compositor system 400C, in accordance with an embodiment of the invention. Referring to FIG. 4D, there is shown a first SBFL 427 c, a plurality of input multiplexers 427 a to 427 d, a plurality of vertical scalers S₀ 429 a to S₃ 429 d, a plurality of output multiplexers 427 e to 427 h, a second SBFL 427 d and a third SBFL 427 e.

FIG. 4D may be viewed as another embodiment combining the configuration of FIG. 4A and FIG. 4B except using the same plurality of vertical scalers S₀ 429 a to S₃ 429 d to perform both vertical and horizontal scaling. The plurality of input multiplexers 427 a to 427 d may be controlled by control logics 405 e to 405 h to switch in either pixel data streams X₀ 414 a to X₃ 414 d from the first SBFL 427 c or X₀ 414 f to X₃ 414 j from the second SBFL 427 d. The plurality of output multiplexers 427 e to 427 h may be controlled by control logics 405 j to 405 n to direct first vertically scaled output pixel data streams Y₀ 418 a to Y₃ 418 d to the second SBFL 427 d for pixel data transposition. An alternate route may be to output a second set of vertically scaled transposed output pixel data streams Y₄ 418 f to Y₇ 418 j to a third SBFL 427 e for a second transposition.

The third SBFL 427 e may perform a second transposition to the twice vertically scaled transposed once output pixel data streams Y₄ 418 f to Y₇ 418 j to generate a twice vertically scaled and twice transposed output pixel data 414 e. A merging function under a control logic 405 p may merge and combine the pixel data 414 e comprising Y′₄ to Y′₇ into a symmetrically scaled image 414 k in both vertical and horizontal directions.

The first, second and third SBFL 427 c, 427 d and 427 e, the plurality of multiplexers 427 a to 427 h and control logics 405 c to 405 p may be programmed to operate in a concerted effort to facilitate vertical scaling to scale vertically and horizontally with the use of the same vertical scalers S₀ 429 a to S₃ 429 d. The sequence of first and second vertical scaling may be reversed to accomplish the same scaling result with a first and second transposition and a merging function.

The functions of FIG. 4A to 4D may be implemented on one or more integrated circuits in conjunction with one or more processors or controllers on a circuit board. In another embodiment of the invention, the functions FIG. 4A to 4D may reside in a host device such as a computer or a work station.

FIG. 5 illustrates an exemplary vertical scale down or scale up processes in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 5, there is shown a multi-pixel memory to memory compositor system 500 comprising a stripe buffer filing logic (SBFL) 527, a plurality of parallel input pixel data streams X₀ 514 a to X₃ 514 d stored in a plurality of memory spaces 515 a to 515 d, a plurality of vertical scalers S₀ 529 a to S₃ 529 d, a phase accumulator control 503 and the plurality of vertical scalers S₀ 529 a to S₃ 529 d respectively, and a plurality of respective parallel output pixel data streams Y₀ 518 a to Y₃ 518 d. The use of four parallel vertical scalers proportionately increases the throughput of pixel scaling per clock cycle by four times in this exemplary illustration. Notwithstanding, the invention is not limited to scaling by four times. Higher or lower throughputs may be controlled by using more or less vertical scalers in parallel arrangement.

In an embodiment of the invention, it may be shown that the SBFL 527 may be 128 pixels wide sending four parallel pixel data streams X₀ 514 a to X₃ 514 d with 32 pixels width each to stripe across four memory buffers 515 a to 515 d. For example, the four memory spaces 515 a to 515 d may each hold up to six vertically neighboring pixels at a time shown as X_(0,0) 514 t to X_(5,0) 514 v, X_(0,1) to X_(5,1), X_(0,2) to X_(5,2), and X_(0,3) to X_(5,3) respectively. In another embodiment of the invention, the memory spaces 515 a to 515 d may each hold more or less than six pixels at a time. In another embodiment of the invention, each of the memory spaces 515 a to 515 d may hold a subsequent stripe of pixels X_(0,4) to X_(5,4), X_(0,5) to X_(5,5), X_(0,6) to X_(5,6), and X_(0,7) to X_(5,7) from the SBFL 527.

FIG. 5 illustrates two exemplary vertical scaling processes, namely a divide by four scale down process and a multiply by five scale up process. A description of a single vertical scaling process by the vertical scaler S₀ 529 a may provide sufficient illustration to the rest of parallel vertical scalers S₁ 529 b to S₃ 529 d.

In a scale down by four process (scaling factor of ¼), the vertical scaler S₀ 529 a may comprise, for example, a five tap FIR filter (process five data points to produce an output). The exemplary five tap FIR filter may be programmed to initially read up to five out of six pixels X_(0,0) to X_(5,0) (one pixel per clock cycle at a time) from the memory space 515 a to generate an initial output pixel Y₀ 518 a. The initial output pixel Y₀ may be initiated at the starting pixel X_(0,0) in the data stream 514 e. A subsequent output pixel Y₀ 518 a may be generated co-located with input pixel-position X_(4,0) 514 u.

Likewise, the output pixel Y₀ 518 a for a next pixel data stream X_(0,4) to X_(5,4) in scaler S₀ 529 a may be sampled and generated at pixels X_(0,4) and X_(4,4). The divide by four scaling shows that the output Y₀ 518 a is generated with a sampling rate of every four pixels in the input pixel data stream X₀ 514 a. The shaded pixels in memory spaces 515 b to 515 d represent the pixel clock cycle locations where respective output pixels Y₁ 518 b to pixel Y₃ 518 d may be generated. The initial pixel sampling point may take place at any pixels within X_(0,0) 514 t to X_(5,0) 514 v. In another embodiment of the invention, the FIR filter calculations may be programmed to use any suitable pixel sampling sizes more than or less than five pixels. Accordingly, the pixel per clock cycle throughput may be multiplied by four times or higher by increasing the number of parallel scalers used.

In a scale up by five process (scaling factor of 5), a five tap FIR filter in the vertical scaler S₀ 529 a may be programmed to read five out of six pixels X_(0,0) to X_(5,0) from the memory buffer 515 a to generate an initial output pixel Y₀ 518 a. In scaling up by five, four additional pixels may be inserted in each of the pixels X_(0,0) to X_(5,0). In an exemplary embodiment of the invention, the pixel X_(2,0) 514 k may be scaled up by five to yield pixels X_(2,0.0) 514 k′ to pixel X_(2,0.8) 514 s with equal pixel spacing (step size) by an interpolation process. The step size is the reciprocal of the scaling factor. In this example, for a scaling factor of five, the step size is 0.2 for interpolation calculation.

The process of FIR filter calculation for scaling and inserted pixel generation may incur additional delays in the scaling process. The initial time taken to generate a scaled up output pixel Y₀ 518 a may comprise the sum of clock cycles for reading the pixel data stream X_(0,0) 514 t to X_(5,0), FIR filter calculations for scaling, insertion and in sending output pixels Y₀ 518 a. The higher the scaling factor, the longer it may take to generate the output pixels Y₀ 518 a.

Likewise, the FIR filter calculations for scaling up may use any suitable pixel sampling sizes more than or less than five pixels. Any combinations of pixel sampling sizes or scaling factors may be used without departing from the spirit of the invention. The scaling up or scaling down of pixels may be processed at a rate of one pixel per clock cycle in the each of the scalers S₀ 529 a to S₃ 529 d. Accordingly the throughput may be multiplied by four times or higher by increasing the number of parallel scalers available.

The input and output scaler paths may use the same phase accumulator and control logic 505 a and 505 b sent from the phase accumulator and control (PAC) 503. The phase accumulator and control 503 may comprise a controller or processor with suitable circuits, logic or codes to manage a plurality of functions in the vertical scaling processes. In this example, the PAC 503 may issue control logics 505 a and 505 b to control the SBFL 527 and the plurality of vertical scalers S₀ 529 a to S₃ 529 d. The PAC 503 may manage the stripe buffer filing logic for partitioning and sending of parallel pixel data streams X₀ 514 a to X₃ 514 d to the memory spaces 515 a to 515 d. In another instance, the phase accumulator and control 503 may control the rate of data flow into the memory spaces 515 a to 515 d. In another instance, the PAC 503 may align the pixels in all data paths 514 e to 514 h to a substantially equal phase value prior to scaling. In another instance, the PAC 503 may communicate information such as scaling parameters for FIR filter calculations, pixel sample sizes i, pixel number n, or other controls such as enable control to the plurality of scalers S₀ 529 a to S₃ 529 d. In another instance, the PAC 503 may control the logic of the multiplexers 427 a to 427 h and the plurality of SBFL 427 c to 427 e for data transposition shown in FIG. 4D.

In the above examples, a four pixel per clock cycle scaling of multi-pixel data streams X₀ 514 a to X₃ 514 d have been illustrated. By increasing the number of parallel vertical scalers, higher throughput of pixels may be scaled proportionately, thus reducing the use of multiple instances and replacing single-pixel scaling to achieve higher throughput.

FIG. 6 is a block diagram that illustrates an exemplary vertical scaler that utilizes fewer pixels per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 6, there is shown a multi-pixel memory to memory compositor system 600 comprising a stripe buffer filing logic (SBFL) 627 controlled by logic 605 a, a plurality of parallel input pixel data streams X₀ 614 a to X₃ 614 d stored in a plurality of memory space 615 a to 615 d, a plurality of multiplexers 627 a to 627 d, a plurality of vertical scalers S0 629 a to S3 629 d, a phase accumulator and control (PAC) block 603 issuing control logic 605 a, 605 b and 609 and a plurality of respective parallel output pixel data streams Y₀ 618 a to Y₃ 618 d from vertical scalers S0 629 a and S1 629 b.

Similar to FIG. 5, the multi-pixel memory to memory compositor system 600 may be modified to process a plurality of input pixel data streams X₀ 614 a to X₃ 614 d using two vertical scalers S0 629 a and S1 629 b controlled by control logic 605 b. The higher capacity architecture may be selectively switched off to a lower capacity in order to conserve power or hardware resources such as selectively switching off vertical scalers S2 629 c and S3 629 d for other needed processes.

The phase accumulator control (PAC) 603 may send control logic 605 a to the SBFL 627 such that input pixel data streams X₀ 614 a and X₁ 614 b may be striped into memory spaces 615 a and 615 b through data paths 614 a and 614 b. Input pixel data streams X₂ 614 c and X₃ 614 d may next be striped into memory spaces 615 c and 615 d through data paths 614 a and 614 b. The multiplexers 627 a and 627 b controlled by control logic 609 may be used to switch in pixel data streams to be read by vertical scalers S₀ 629 a and S₁ 629 b from data paths 614 e to 614 h for vertical scaling.

In this example, control logic 609 from the PAC 603 may control the multiplexers 627 a and 627 b to switch in data paths 614 e and 614 f to read pixels X_(0,0) to X_(5,0) and X_(0,1) to X_(5,1) from memory spaces 615 a and 615 b for scaling by vertical scalers S₀ 629 a and S₁ 629 b. Upon completion of scaling pixels X_(0,0) to X_(5,0) and X_(0,1) to X_(5,1), the control logic 609 may control the multiplexers 627 a and 627 b to switch in data paths 614 g and 614 h to read pixels X_(0,2) to X_(5,2) and X_(0,3) to X_(5,3) from memory spaces 615 c and 615 d for scaling by vertical scalers S₀ 629 a and S₁ 629 b. This operation may repeat using two vertical scalers S₀ 629 a and S₁ 629 b to process a plurality of input pixels data streams at an effective processing rate of two pixels per clock cycle. Similarly, a one pixel per clock cycle processing rate may utilize the multiplexer 627 a to switch in pixels from data paths 614 e to 614 h for scaling one data stream at a time in sequential order or any desired order.

In another embodiment of the invention, the remaining unused vertical scalers 629 c and 629 d may be configured as a second vertical scalers to scale transposed output pixel data streams Y₀ 414 a to Y₃ 414 d to accomplish horizontal scaling. Such configuration of partitioning or sharing vertical scaler resources to perform vertical and horizontal scaling may be implemented with the use of a second SBFL and a plurality of multiplexers as shown in FIGS. 4B and 4C.

FIG. 7A is a block diagram that illustrates exemplary horizontal scaling using a single-pixel per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 7A, there is shown an input pixel data stream 714 X₀, X₁, X₂, X_(n), . . . , a plurality of horizontal scalers S0 729 a to S3 729 d and an output pixel data stream Y_(n) 724 a. The input pixel data stream 714 may comprise sequential pixels X₀, X₁, X₂, X_(n), . . . where each pixel has at least one horizontal neighbor.

In an embodiment of the invention, horizontal scaling may be done by a single-pixel horizontal scaler S₀ 729 a in a multi-pixel memory to memory compositor system in FIG. 7A. Each of the horizontal scalers S₀ 729 a to S₃ 729 d may comprise a FIR filter calculating an output pixel Y_(n) 724 a using horizontal neighboring pixels X₀, X₁, X₂, X_(n), . . . for calculations. For example, if the scaler S₀ 729 a uses a five tap FIR filter, the output pixel data stream Y_(n) 724 a may be calculated using input horizontal neighboring pixels X_(n−2), X_(n−1), X_(n), X_(n+1) and X_(n+2).

It may take the scaler S₀ 729 a at least a clock cycle to read in a new pixel from the input data stream 714. For example, if the scaling factor is one, it may take a clock cycle to output Y_(n) to Y_(n+1) where Y_(n) and Y_(n+1) may be calculated from horizontal neighboring pixels X_(n−2), X_(n−1), X_(n), X_(n+1), X_(n+2) and X_(n−1), X_(n), X_(n+1), X_(n+2), X_(n+3) respectively. In another embodiment of the invention, if the scaling factor is two in the scaler S₀ 729 a, the output pixel data stream Y_(n) 724 a may comprise two output pixels Y_(n,0) and Y_(n,1) calculated from horizontal neighboring pixels X_(n−2), X_(n−1), X_(n), X_(n+1) and X_(n+2). In generating two output pixels Y_(n,0) and Y_(n,1), the single-pixel horizontal scaler S₀ 729 a may require at least two clock cycles to complete scaling of two for every input pixel X_(n) read into the scaler S₀ 729 a. The scaler S₀ 729 a processing efficiency may be reduced by a factor of two accordingly. This example may be further illustrated in scenario 800 a in FIG. 8.

Using a single-pixel horizontal scaler to perform scale up or scale down operation is analogous to using a vertical scaler S₀ 429 a to process a plurality of transposed input data streams X₀ 414 a to X₃ 414 d where the vertical neighbor pixels (presumably stored in a memory space 415 a) become an equivalent of horizontal neighbor pixels across a row 414 e as shown in FIG. 4A.

FIG. 7B is a block diagram that illustrates exemplary horizontal scaling using two pixels per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 7B, there is shown an input multi-pixel data stream X₀ X₁, X₂, X_(n), . . . 734, a plurality of horizontal scalers S₀ 729 a to S₃ 729 d and two output pixels Y_(n,0) 744 a to Y_(n,1) 754 a.

With an understanding that the efficiency of vertical scaling may be increased by parallelizing vertical scalers, likewise horizontal scaling may be increased by parallelizing horizontal scalers. However, each of the horizontal scalers S₀ 729 a to S₃ 729 d may process the same sequence of pixels (i.e. same row of pixels 414 e shown in FIG. 4A) instead of processing vertical sequences of pixels (i.e. columns of pixels in memory spaces 415 a to 415 d shown in FIG. 4A).

For example, FIG. 7B illustrates an alternate horizontal scale by two process adapted to a two pixel per clock cycle operation using two scalers S₀ 729 and S₁ 729 b each processing a same input pixel X_(n) in a clock cycle (from a sequence of horizontal neighboring pixels X_(n−2), X_(n−1), X_(n), X_(n+1), X_(n+2)). Horizontal scaling of the sequential pixels X_(n−2), X_(n−1), X_(n), X_(n+1), X_(n+2) may have a complex problem because the adjacent horizontal pixels scaling operation in each of the horizontal scaler S₀ 729 or S₁ 729 b may not be separable. The same pixel X_(n) may be replicated and read as input pixels X_(n,0) 734 aa to X_(n,1) 734 ab, each differs by a step-size and an initial phase parameters, by horizontal scalers S₀ 729 a and S₁ 729 b respectively.

Two output pixels Y_(n,0) 744 a to Y_(n,1) 754 a may be calculated from respective input pixels X_(n,0) 734 aa to X_(n,1) 734 ab from horizontal neighboring pixels X_(n−2), X_(n−1), X_(n), X_(n+1), X_(n+2) in the five tap FIR filters in horizontal scalers S₀ 729 a and S₁ 729 b respectively. The two output pixels Y_(n,0) 744 a to Y_(n,1) 754 a may represent doubling the scaling factor by parallel horizontal scalers S₀ 729 a and S₁ 729 b where two output pixels Y_(n,0) 744 a to Y_(n,1) 754 a are generated from an input pixel X_(n) without the penalty of consuming two clock cycles in each of the horizontal scalers S₀ 729 a and S₁ 729 b. Therefore doubling the parallel horizontal scalers may double the pixel processing efficiency by two correspondingly. In an alternate embodiment of the invention, each of the two parallel horizontal scalers S₀ 729 a and S₁ 729 b may be programmed with a scaling factor of two to produce an effective scaling factor of four.

FIG. 7C is a block diagram that illustrates exemplary horizontal scaling using four pixels per clock cycle in a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Referring to FIG. 7C, there is shown an input multi-pixel data stream X₀, X₁, X₂, X_(n), . . . 764, a plurality of horizontal scalers 729 a to 729 d and output pixels Y_(n,0) 774 a, Y_(n,1) 784 a, Y_(n,2) 794 a and Y_(n,3) 768 a.

FIG. 7C is an extension of FIG. 7B, which illustrates exemplary quadrupling of the horizontal scalers 729 a to 729 d to achieve an effective scaling factor of four. In this regard, four output pixels Y_(n,0) 774 a to Y_(n,1) 768 a may be generated from an input pixel X_(n) without the penalty of consuming four clock cycles if performed by a single horizontal scaler. Accordingly the same pixel X_(n) may be replicated and read as input pixels X_(n,0) 764 aa to X_(n,1) 764 ad horizontal scalers S0 729 a to S3 729 d respectively. Each of the read input pixels X_(n,0) 764 aa to X_(n,1) 764 ad may differ by a step-size and an initial phase parameters.

Contrary to parallel vertical scaling in FIG. 5, where each of the vertical scalers 529 a to 529 d may be controlled by the same control logic 505 b from the phase accumulator control 503, each of the plurality of horizontal scalers 729 a to 729 d may be independently phase controlled by a plurality of control logic. Each of the output pixels X_(n,0) 764 aa to X_(n,1) 764 ad scaled by the plurality of horizontal scalers 729 a to 729 d may have a different initial phase angle. A high scaling factor (scale up or scale down) may accumulate sufficient phase delays or pixel separations due to step sizes. The phase angle and step size problems may be illustrated by scenario 800C in FIG. 8

FIG. 8 is a block diagram that illustrates exemplary phase and step size relationship of output pixels from a plurality of parallel horizontal scalers, in accordance with an embodiment of the invention. Referring to FIG. 8, there is shown a scenario 800A of scaling up by two operating at a single-pixel per clock cycle using a single horizontal scaler, a scenario 800B of scaling up by two operating at an effective two pixels per clock cycle by using two parallel horizontal scalers and a scenario 800C of scaling up by four operating at an effective four pixels per clock cycle by using four parallel horizontal scalers.

Scenario 800A illustrates the phase angle and step size relationship of output pixel Y_(n) 724 a from scaler S₀ 729 a shown in FIG. 7A. An Input pixel (source pixel) X_(n) may be represented as a circle. For example X_(n) with values of n=3, 4, 5, 6, and 7 (n being the pixel position) may be depicted as X₃ 814 a to X₇ 814 e. Output pixels Y_(3,0) 824 a and Y_(3,1) 824 b may be represented by a cross being calculated from horizontal neighboring pixels X₁, X₂ (do not exist or have no value in this example), X₃ 814 a, X₄ 814 b and X₅ 814 c using a five tap FIR filter in scaler S₀. Since neighboring pixels X₁, X₂ do not have values, in an instance, pixel X₃ 814 a may be repeated three times to replace X₁, X₂ in the calculation. Similarly, output pixels Y_(6,0) 824 g and Y_(6,1) 824 h may be calculated from horizontal neighboring pixels X₄ 814 b, X₅ 814 c, X₆ 814 d, X₇ 814 e and X₈ (not exist) in scaler S₀ and X₇ 814 e may be repeated twice to replace X₈ for calculations.

The initial output pixel Y_(3,0) 824 a may carry a phase angle φ representing an initial phase delay, the second output pixel Y_(3,1) 824 b may be separated by a step size of s 804 a, where s 804 a is the reciprocal of the scaling factor per clock cycle. In this example, if the scaling factor is two (Sx=2), the step size s 804 a (s=½). For a subsequent input pixel X₄ 814 b, the outputs Y_(4,0) 824 c and Y_(3,0) 824 a may be separated by the a value of step size 2s (sum of 804 a and 804 b).

Although the step size s 804 a between output pixels Y_(3,0) 824 a and Y_(3,1) 824 b may be half of pixel sampling distance, generating either output Y_(3,0) 824 a or Y_(3,1) 824 b may each consume a full clock cycle per pixel. In this example, the scaler S₀ may consume one input pixel X₃ 814 a at a peak rate of one pixel per clock cycle, assuming no initial phase angle φ 802 a as delay, the scaler S₀ would have to wait for at least two clock cycles to clear the outputs pixels Y_(3,0) 824 a and Y_(3,1) 824 b. Therefore, the effective time required to process one input pixel X_(n) per clock cycle having a scaling factor of two would require at least two clock cycles.

Scenario 800B illustrates the phase angle and step size relationship of output pixels Y_(n,0) 744 a and Y_(n,1) 754 a from scalers S₀ 729 a and 729 b respectively shown in FIG. 7B. For example X_(n) with values n=3, 4, 5, 6, and 7 may be depicted as X₃ 834 a to X₇ 834 e. Output pixel Y_(3,0) 844 a may be represented by a cross may be calculated from horizontal neighboring pixels X₁, X₂, (not shown), X_(3,0) 834 a, X_(4,0) 834 b and X_(5,0) 834 c using a five tap FIR filter in scaler S₀. Similarly, output pixel Y_(3,1) 854 a represented by a crossed square may be calculated from horizontal neighboring pixels X₁, X₂ (not shown), X_(3,0) 834 a, X_(4,0) 834 b and X_(5,0) 834 c in scaler S₁. Similarly, output pixels Y_(6,0) 844 d and Y_(6,1) 854 d may be calculated from horizontal neighboring pixels X_(4,0) 834 b, X_(5,0) 834 c, X_(6,0) 834 d, X_(7,0) 834 e and X_(8,0) (not shown) in scaler S₀ and X_(4,0) 834 b, X_(5,0) 834 c, X_(6,0) 834 d, X_(7,0) 834 e and X_(8,0) (not shown) in scaler S1.

The phase angle and step size values derived by hardware for each of these parallel horizontal scalers may be defined by the following relationships:

-   -   s=1/(Sx)), where Sx being the scaling factor, s being the step         size per scaler,     -   s′=s*N, where s′ being the new step size per N scalers,     -   φ_(n)=φ+(N−1)*s, where φ 802 a is the initial phase angle, and         φ_(n) is the phase angle for n-th scaler in the group.         In the above relationships, N defines the numerical quantity of         scalers used, which is related to how many pixels may be         processed per clock cycle. In the examples used, N may take         values of 1, 2 or 4 in scenarios 800A, 800B or 800C.         Notwithstanding, the invention may not be so limited and N may         take on other values.

-   nε{0, 1, . . . N−1} n being the identity of the scaler, for example,     n would be 0 for scaler S0, 1 for scaler S1 and so on.     Knowing the phase value and step size (reciprocal of scaling     factor—a user input), the multi-pixel memory to memory compositor     system new step size and phase angle values for the output pixels     may be calculated.

The concept of adjusting the phase and step-size to achieve higher throughput may be illustrated in scenario 800B with two parallel scalers. For N=2, the phase and step parameters are defined as:

-   -   s′=2s, (step size S′ 810 a—separation between subsequent pixels         in the same scaler output)     -   φ₀=φ, (phase angle φ₀ 802 b for pixel Y_(3,0) 844 a)         φ₁=φ+s, (phase angle φ₁ 802 c for pixel Y_(3,1) 854 a)

The initial output pixel Y_(3,0) 844 a by scaler S0 may carry a phase angle φ₀ 802 b representing an initial phase delay, the second output pixel Y_(3,1) 854 b by scaler S1 may carry a phase angle φ₁ 802 b. The output pixels Y_(3,0) 844 a and Y_(3,1) 854 a may be processed within a substantially similar clock cycle where scalers S0 and S1 may be independently phase controlled due to the differences in phase angles φ₀ 802 b and φ₁ 802 b.

In this scenario, an effective two pixels per clock cycle may be achieved where two output pixels Y_(3,0) 844 a and Y_(3,1) 854 a are generated by two horizontal scalers S0 and S1 each with a scaling factor or one for the input pixels X₃ X₃ X₃ X₄ X₅ of input pixel data stream 834. Likewise, an effective scaling factor of two may be produced from the two parallel horizontal scalers S0 and S1.

The outputs Y_(4,0) 844 b and Y_(4,1) 854 b may be each separated by the same value of step size s′ 810 a and 810 b from outputs Y_(3,0) 844 a and Y_(3,1) 854 a. The outputs for example, Y_(3,0) 844 a and Y_(3,1) 854 a of the scalers S0 and S1 may not be produced at the same time (shown with differing phase angles φ₀ 802 b and φ₁ 802 c) and buffering may be required at the output of each of the individual scalers S0 to S1 for performing a proper interleaving of outputs.

Scenario 800C further illustrates the phase angles and step size relationship of output pixels Y_(n,0) 774 a, Y_(n,1) 784 a, Y_(n,2) 794 a and Y_(n,2) 768 a from scalers S0 729 a to 729 d respectively shown in FIG. 7C. For example X_(n) with values n=3 and 4 may be depicted as X₃ 864 a and X₄ 864 b. The output pixel Y_(3,0) 874 a may be represented by a cross may be calculated from horizontal neighboring pixels X_(1,0), X_(2,0) (not exist), X_(3,0) 864 a, X_(4,0) 864 b and X_(5,0) 864 c using a five tap FIR filter in scaler S0. Similarly, the output pixel Y_(3,1) 884 a represented by a crossed square may be calculated from horizontal neighboring pixels X_(1,0), X_(2,0) (not exist), X_(3,0) 864 a, X_(4,0) 864 b and X_(5,0) 864 c in scaler S1.

Similarly, output pixel Y_(3,2) 894 a represented by a crossed circle may be calculated from horizontal neighboring pixels X_(1,0), X_(2,0) (do not exist or have no value in this example), X_(3,0) 864 a, X_(4,0) 864 b and X_(5,0) 864 c in scaler S2. Similarly, output pixel Y_(3,3) 868 a represented by a crossed bolded may be calculated from horizontal neighboring pixels X_(1,0), X_(2,0) (do not exist or have no value in this example), X_(3,0) 864 a, X_(4,0) 864 b and X_(5,0) 864 c in scaler S3. Similarly, output pixels Y_(4,0) 874 b to Y_(4,3) 868 b may be calculated from similar calculations in scalers S0 to S3.

Output pixels Y_(3,1) 884 a to Y_(3,3) 868 a may be processed within a substantially same clock cycle where scalers S0 to S3 may be independently controlled due to the difference in phase angles φ₀ 802 d, φ ₁ 802 e, φ ₂ 802 f and φ₃ 802 g.

In this scenario, an effective four pixels per clock cycle may be achieved where four output pixels Y_(3,0) 874 a to Y_(3,3) 868 a may be generated by four horizontal scalers S0 to S3 each with a scaling factor or one for the input pixel X₃ of input pixel data stream 864. Likewise, an effective scaling factor of four may be produced from the four parallel horizontal scalers S0 to S4.

For a subsequent input pixel X₄ 864 b, the outputs Y_(4,0) 874 b and Y_(4,3) 868 b may be each separated by the same value of step size s″ 812 a and 812 b from outputs Y_(3,0) 874 a and Y_(3,3) 868 a.

FIG. 9A is a block diagram that illustrates exemplary multi-pixel per clock cycle horizontal scaler for a multi-pixel memory to memory compositor system 900A, in accordance with an embodiment of the invention. Referring to FIG. 9A, there is shown an input multi-pixel data stream 964, a distributor control 903 a, a phase accumulator control (PAC) 903 c with a plurality of control logics 909 a to 909 d, a plurality of horizontal neighboring pixels X_(3,0) 964 aa to X_(3,3) 964 ad, a plurality of parallel horizontal scalers S0 929 a to S1 929 d, a plurality of output pixels Y_(3,0) 974 a, Y_(3,1) 984 a, Y_(3,2) 994 a and Y_(3,3) 968 a, a merge control 903 b and an output multi-pixel data stream Y₀ Y₁ Y₂ to Y_(n) 919.

The input pixel data stream 964 may comprise a sequence of pixels X₀ 964 a to X_(n) 964 n read by the distributor control 903 a. The distributor control 903 a may comprise suitable logic, circuitry, and/or code that may enable control to replicate and broadcast a plurality of horizontal neighboring pixels such as pixels X_(3,0) 964 aa to X_(3,3) 964 ad to the scalers S0 929 a to S1 929 d. In an embodiment of the invention, the distributor control 903 a may comprise memory or a multiplexer controlled by logic.

Each of the plurality of horizontal scalers such as scaler S0 929 a may comprise an alignment buffer 931 a, a scaler control 933 a and an alignment buffer 935 a. In an embodiment of invention, four horizontal scalers S0 929 a to S3 929 d, an alignment buffer 931 a in scaler S0 929 a may comprise a memory buffer with a tri-state logic or a shift register. The alignment buffer 931 a may allow the input data such as pixels X_(4,0) to X_(4,3) to be out of sync The alignment buffer 931 a may also keep the next four pixels X_(3,0) 964 aa to X_(3,3) 964 ad ready so that they may be pushed into the scaler data paths 932 a to 932 d, (whenever the data path 932 a to 932 d may be ready to accept pixel data). In other words, it may ensure that clock cycles are not wasted in aligning the pixels X_(3,0) 964 aa to X_(3,3) 964 ad for a scaling up operation.

A phase accumulator PAC 903 c and the respective control logic 909 a to 909 d associated with each of the data paths 932 a to 932 d may derive information on how many input pixels are required to be shifted in, and may accept those many pixels from the alignment buffers 931 a to 931 d.

The Scalers S0 929 a to S1 929 d may each comprise a FIR filters to perform scaling functions described in FIG. 4A. The outputs from scalers S0 929 a to S1 929 d may go to the an alignment buffer 935 a to 935 d due to out of sync caused by cumulative phase shifts and step size separations from scaler S0 929 a to S1 929 d. Each of the an alignment buffer 935 a to 935 d may comprise a buffer that may be required to provide buffering to avoid lockup/pipeline-stall conditions in the data paths 932 e to 932 h, particularly in a scale down operation with a scale down factor being a high numerical value.

In an alternate embodiment of the invention, the parallel horizontal scalers 929 a to 929 d may be configured to process vertical scaling with transposed pixel data from the input pixel data stream 964 using a plurality of buffers to transpose data for after horizontal scaling.

FIG. 9B is a block diagram that illustrates exemplary use of four horizontal scalers for both horizontal and vertical scaling in a multi-pixel memory to memory compositor system 900B, in accordance with an embodiment of the invention. Refer to FIG. 9B, there is shown pictorially that the operations of FIG. 9A may be cascaded with a second buffer 927 b to transposed output 919, a second horizontal scalers 929 e to 929 h and a third buffer 927 c to transpose output 919 c to generate an image 964 t that is symmetrically scaled four times vertically and horizontally.

An image may be stored as pixel data 964. The pixel data 964 may be read by a first buffer 927 a and sent as a sequential pixel data streams X₀ to X_(n) to be read by a first four horizontal scalers 929 a to 929 d. The first four horizontal scalers 929 a to 929 d may horizontally scale the pixel data streams X₀ to X_(n) 964 with a scaling factor, in this illustration quadrup ling the horizontal dimension as first horizontally scaled output pixel data streams Y₀ to Y₃ 919. The first horizontally scaled output pixel data streams Y₀ to Y₃ 919 may be read by a second buffer 927 b and be transposed as input pixel data streams X_(0,0) to X_(3,0) 919 a.

The transposed input pixel data streams X_(0,0) to X_(3,0) 919 a may be read by a second four horizontal scalers 929 e to 929 h and be horizontally scaled a second time to a twice horizontally scaled transposed output pixel data streams Y₄ to Y₇ 919 c. The twice horizontally scaled transposed output pixel data streams Y₄ to Y₇ 919 c may be read by a third buffer 927 f where a second transposition may take place to generate a twice horizontally scaled, twice transposed output pixel data streams Y′₄ to Y′₇ 919 d. Since the pixel data leaving the second horizontal scalers 929 e to 929 h may have already been merged, the third buffer 927 f may output a single image 964 t with a symmetrically scaled by four times image 964 t both vertically and horizontally.

FIG. 10 is a flow chart that illustrates exemplary steps for vertical scaling of a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Reference designations of FIGS. 4A to 4B may be referred to at various steps in the flow chart method 1000. At step 1002, read video data from memory. Video data 414 a may be read into SBFL 427 a. At step 1004, stripe video data as parallel pixel data streams to vertical scalers. The SBFL 427 a may stripe the video data 414 a into a plurality of parallel pixel data streams X₀ 414 a to X₃ 414 d to be sent to a plurality of parallel vertical scalers S0 429 a to S3 429 d. Each of the pixel data streams may comprise a plurality of pixel data, for example X_(0,0) to X_(5,0) for pixel data stream X₀ 414 a.

At step 1006, parallel pixel data streams may be read into the in FIR filters. Each of the FIR filters in the plurality of parallel vertical scalers S0 429 a to S3 429 d may read the plurality of pixel data from respective parallel pixel data streams X₀ 414 a to X₃ 414 d. At step 1008, pixel data may be processed per A scaling factor, the latter of which may be read from a user input or from a preprogrammed value. The scaling factor may determine the step size of the output pixels for scaling up or scaling down. An output Y₀ 418 a may be generated based on the vertical neighboring pixel data X_(0,0) to X_(5,0) in the pixel data stream X₀ 414 a.

At step 1010, output parallel pixel data streams may be generated. Each of the parallel outputs Y₀ 418 a to Y₃ 418 d may comprise a sequence of scaled pixel data. Step 1012 determines if a next pixel may be available. The logic control 405 a from a phase accumulator control (not shown in FIG. 4A) may continue to stripe video data 414 a for vertical scaling by returning to step 1002 until the vertical scaling process may be completed. At step 1014, the output pixel data from the plurality of parallel data streams may be merged and output as a scaled image or stored in a memory buffer.

In another embodiment, step 1002 may be modified to read transposed first vertically scaled video data 414 b into a second SBFL 427 b. The second SBFL 427 b may stripe the transposed pixel data streams X₀ 414 f to X₃ 414 j such that horizontal scaling may be achieved using vertical scalers S0 429 e to S3 429 h as shown in FIG. 4B.

FIG. 11 is a flow chart that illustrates exemplary steps for horizontal scaling of a multi-pixel memory to memory compositor system, in accordance with an embodiment of the invention. Reference designations of FIG. 9A may be referred to at various steps in the flow chart or method 1100. At step 1102, sequential pixel data stream may be read from memory. Video data as sequential pixel data stream 964 may be read into a memory buffer, such as a buffer with distributor control 903 a. At step 1104, pixel data may be replicated, distributed, and aligned to horizontal scalers. The distributor control 903 a may replicate each incoming pixel X₀ 964 a to X_(n) 964 n in the sequential pixel data stream 964 into a plurality of identical pixels X_(3,0) 964 aa to X_(3,3) 964 ad to be distributed to a plurality of parallel horizontal scalers S0 929 a to S3 929 d.

At step 1106, the pixel data may be aligned, and shifted to horizontal scalers. To facilitate horizontal scaling operation in horizontal scalers S0 929 a to S3 929 d, the replicated pixel data X_(3,0) 964 aa to X_(3,3) 964 ad may need to arrive the scalers S0 929 a to S3 929 d at different time or different pixel clock cycles explained in FIG. 9A. The alignment buffer 931 a to 931 d may accommodate pixel data to be out of syn by a determined number of pixels. When any of the horizontal scalers S0 929 a to S3 929 d may be ready to process pixel, the alignment buffers 931 a to 931 d may shift the pixel data in.

At step 1108, the aligned pixel data may be read in FIR filter. Each of the FIR filters may read in a respective aligned pixel data to be processed along with other aligned horizontal neighbor pixels exist in the respective FIR filter. If no new aligned pixel data may be read, existing aligned pixel data in the FIR filter may be reused for processing. At step 1110, pixel data may be processed per a scaling factor. The respective FIR filter in each of the horizontal scalars may perform scaling operation on the aligned pixel data per a defined scaling factor. The scaling factor may be defined by a user or from a preprogrammed value.

At step 1112, output scaled sequential pixel data streams may be buffered, aligned, and merged. The scaled outputs may have different phase angles and different step size separations depending on the value of scaling factor and the number of horizontal scalers used. To avoid a lock up/pipeline stall condition in the horizontal scalars, the output pixel data may be buffered with an alignment buffer 935 a to 935 d so that a new pixel may be read by any of the horizontal scalers. The output from the ping-pong module may be aligned and merged into a scaled sequential pixel data stream.

Step 1114 may determine whether a next pixel may be available or a next output needs to be produced. The logic control 909 a to 909 d from a phase accumulator control (not shown in FIG. 9A) may continue to read sequential pixel data stream 964 for horizontal scaling by returning to step 1102 until the horizontal scaling process may be completed.

In an alternate embodiment of the invention, step 1102 may be modified to read transposed first horizontally scaled sequential pixel data from a second memory buffer. The second memory buffer map the transposed pixel data vertically such that vertical scaling may be achieved using horizontal scalers S0 929 a to S3 929 d.

In accordance with various embodiments of the invention, the method 1000 and 1100, and system 400A to 400 c and 900 A to 900B for processing video data using multi-pixel scaling in a memory system are provided. The multi-pixel scaling using the method or program may include reading pixel data for one or more data streams from the memory system into one or more scalers, wherein each of the plurality of data streams includes a plurality of pixels, scaling the pixel via the one or more scalers and outputting the scaled pixels from the one or more scalers. Pixel data may be sequential 964 or parallel 414 a to 414 d. The plurality of scalers S0 to S₃ 429 a to 429 d or 929 a to 929 d may be in parallel, scaling sequential pixel data 964 with independent phase control logic 909 a to 909 d, or scaling parallel pixel data in substantially equal phase control logic 505 a or 505 b.

Vertically scaled and transposed pixel data 414 m, 414 n, 414 t, may be further read and scaled by vertical scalers S0 to S₃ 429 a to 429 d. The output generated from the scalers may be transposed and merged together as a symmetrically scaled image 414 h. Horizontally scaled and transposed pixel data 919 a may be further read and scaled by horizontal scalers 929 f. The outputs may be aligned and merged as pixel data 919 c. The output pixel data 919 c may be further transposed to pixel data 919 d and may be displayed as a symmetrically scaled image 964 t. Scaling may comprise interpolation or sub sampling using pixel phase angle φ, position n, step size s and scaler quantities N.

Accordingly, the present invention may be realized in hardware, software, or a combination of hardware and software. The present invention may be realized in a centralized fashion in at least one computer system or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software may be a general-purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein.

The present invention may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which when loaded in a computer system is able to carry out these methods. Computer program in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to another language, code or notation; b) reproduction in a different material form.

While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims. 

1. A method for processing video data, the method comprising: striping pixel data from a buffer into a plurality of data streams, wherein each of said plurality of data streams comprises a plurality of pixels; scaling, in parallel, said plurality of pixels from each of said plurality of data streams, utilizing a corresponding plurality of scalers; and outputting, in parallel, said scaled plurality of pixels from each of said corresponding plurality of scalers.
 2. The method according to claim 1, wherein said pixel data comprises sequential pixel data.
 3. The method according to claim 2, comprising replicating said sequential pixel data prior to said scaling.
 4. The method according to claim 3, comprising distributing adjacent sequential pixel data associated with said replicated sequential pixel data subsequent to said scaling.
 5. The method according to claim 1, comprising merging said scaled plurality of pixels from each of said corresponding plurality of scalers into a single output data stream.
 6. The method according to claim 1, wherein said pixel data comprises parallel pixel data.
 7. The method according to claim 1, comprising aligning said plurality of pixels from each of said plurality of data streams prior to said scaling.
 8. The method according to claim 1, comprising aligning said scaled plurality of pixels from each of said corresponding plurality of scalers.
 9. The method according to claim 1, comprising scaling said pixel data utilizing independent phase control interpolation in each of said corresponding plurality of scalers.
 10. The method according to claim 9, wherein said independent phase control interpolation utilizing parameters comprising: a pixel phase angle, a step size, a pixel position of said pixel data and a numerical quantity of said corresponding plurality of scalers.
 11. The method according to claim 1, wherein said scaling of said pixel data comprises in-phase control interpolation.
 12. The method according to claim 1, comprising managing reading of said pixel data from said buffer using stripe buffer filling logic.
 13. The method according to claim 1, comprising transposing said pixel data from a memory system prior to said scaling.
 14. A system for processing video data, the system comprising: one or more circuits, said one or more circuits being operable to stripe pixel data from a buffer into a plurality of data streams, wherein each of said plurality of data streams comprises a plurality of pixels; a corresponding plurality of scalers operable to scale in parallel, said plurality of pixels from each of said plurality of data streams; and said one or more circuits being operable to output in parallel said scaled plurality of pixels from each of said corresponding plurality of scalers.
 15. The system according to claim 14, wherein said pixel data comprises sequential pixel data.
 16. The system according to claim 15, wherein said one or more circuits replicates said sequential pixel data prior to said scaling.
 17. The system according to claim 16, wherein said one or more circuits distributes adjacent sequential pixel data associated with said replicated sequential pixel data subsequent to said scaling.
 18. The system according to claim 14, wherein said one or more circuits merges said scaled plurality of pixels from each of said corresponding plurality of scalers into a single output data stream.
 19. The system according to claim 14, wherein said pixel data comprises parallel pixel data.
 20. The system according to claim 14, wherein said one or more circuits aligns said plurality of pixels from each of said plurality of data streams prior to said scaling.
 21. The system according to claim 14, wherein said one or more circuits aligns said scaled plurality of pixels from each of said corresponding plurality of scalers.
 22. The system according to claim 14, wherein said each of said corresponding plurality of scalers scales said pixel data utilizing independent phase control interpolation in each of said corresponding plurality of scalers.
 23. The system according to claim 22, wherein said independent phase control interpolation utilizing parameters comprising: a pixel phase angle, a step size, a pixel position of said pixel data and a numerical quantity of said corresponding plurality of scalers.
 24. The system according to claim 14, wherein said corresponding plurality of scalers scales said pixel data utilizing in-phase control interpolation.
 25. The system according to claim 14, wherein said one or more circuits manages reading of said pixel data from said buffer using stripe buffer filling logic.
 26. The system according to claim 14, wherein said one or more circuits transposes said pixel data from a memory system prior to said scaling.
 27. A non-transitory computer-readable medium having stored thereon, a computer program having at least one code section for processing video data, the at least one code section being executable by a computer for causing the computer to perform steps comprising: striping pixel data from a buffer into a plurality of data streams, wherein each of said plurality of data streams comprises a plurality of pixels; scaling, in parallel, said plurality of pixels from each of said plurality of data streams, utilizing a corresponding plurality of scalers; and outputting, in parallel, said scaled plurality of pixels from each of said corresponding plurality of scalers.
 28. The method according to claim 1, comprising performing one or more operations of: color keying, color conversion, blending or raster operation on said plurality of pixel streams.
 29. The system according to claim 14, wherein said one or more circuits perform one or more operations of: color keying, color conversion, blending or raster operation on said plurality of pixel streams.
 30. The non-transitory computer-readable medium according to claim 27, wherein said at least one code section comprises code for performing one or more operations of: color keying, color conversion, blending or raster operation on said plurality of pixel streams. 